This invention relates generally to global contactors and specifically to a contact block utilizing tool free mechanisms for installation and for changing the state of individual poles.
A conventional electrical contactor in one form typically comprises an electromagnetically actuated device having a magnetic core proximate an armature. Typically, a coil is electrically energized to draw the armature to the magnetic core. The electromagnetically actuated device may be a control relay, a contactor, a motor starter or the like. The armature is operatively associated with a movable device such as an actuator. With an electrical switching apparatus the actuator operates a contact assembly.
A contact assembly may be an integral component of the electrical switching apparatus or it may be an auxiliary device to be added thereto. In either case, the contact assembly typically includes a contact having a pair of stationary contacts and a movable contact. The stationary contacts are fixedly mounted in spaced relation with one another. The movable contact is mounted to the pusher. The contact assembly may provide for normally open contact operation or normally closed contact operation. In some conventional contact designs a different geometry stationary contact is used for normally open and normally closed stationary contact.
A contact block may include a multitude of contacts. However, if additional contacts are required an additional contact block must be added or an auxiliary contact block is added to the end of the contact block. In this configuration the entire contact block must be removed and replaced to increase the number of auxiliary contact blocks.
Additionally, different variations of contact assemblies may require the availability of multiple pusher or auxiliary contact block designs based on the location and orientation of the movable contacts. For example, both contacts can be normally opened, both contacts can be normally closed, one contact can be normally open and the other normally closed. Additionally, the timing of one contact opening and the other closing can also be altered. These variations necessitate additional parts inventory resulting in loss of economies of scale.
The typical contact typically has either two or four poles. If additional poles are needed, a series of single pole auxiliary contacts must be assembled individually on to the contactor. Further, each pole is either normally open or normally closed from the factory. The same device cannot be used in a changed state.
In high voltage applications arcs of electricity crosses the gap as the contacts are closed. Each time an arc occurs carbon scarring or buildup occurs. The carbon scarring over time can reduce the reliability of the contact.
Accordingly, there is a need for a contact assembly for use in an electrical switching apparatus designed to facilitate ease of use, and minimize installation and inventory cost.